Re: [ietf-smtp] Stray <LF> in the middle of messages

John C Klensin <john-ietf@jck.com> Sat, 06 June 2020 20:09 UTC

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Date: Sat, 06 Jun 2020 16:09:13 -0400
From: John C Klensin <john-ietf@jck.com>
To: Paul Smith <paul@pscs.co.uk>
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Subject: Re: [ietf-smtp] Stray <LF> in the middle of messages
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Sorry, that should have been a reference to the next-to-last
paragraph of Section 8 of RFC 6409.  But the principle (and,
with the exception of handwaving about extensions, the text) are
unchanged.

  john


--On Saturday, June 6, 2020 16:03 -0400 John C Klensin
<john-ietf@jck.com> wrote:

> 
> 
> --On Saturday, June 6, 2020 19:36 +0100 Paul Smith
> <paul@pscs.co.uk> wrote:
> 
>> ... 
>> I suppose with a submission server you could be more flexible,
>> but, to be honest, I've *never* come across a case where not
>> treating a lone LF as a line break has been a problem.
>> ...
> 
> And that is exactly why the last sentence of the introductory
> paragraph of Section 8 of RFC 4409 says:
> 
> 	"Any message forwarded or delivered by the MSA MUST
> 	conform to the requirements of [SMTP-MTA] and
> 	[MESSAGE-FORMAT]."
> 
> In other words, perfectly reasonable for a submission server to
> reach a local agreement that bare LFs are to be treated as line
> terminators but, by the time the message reaches the public
> Internet, it needs to have fixed those.
> 
>     john
>